winnow
verb [ T ] uk/ˈwɪn.əʊ/ us/ˈwɪn.oʊ/
扬，簸（谷物）
to blow the chaff (= the outer coverings) from grain before it can be used as food
formal筛选，挑选
to reduce a large number of people or things to a much smaller number by judging their quality
A list of 15 applicants has been winnowed down to three. 15名候选人已经筛选到只剩3人。
a winnowing process 筛选过程